International Comparison on the Application of Societal Risk Criteria

Quantitative risk assessment is now a common tool used for planning and approval of high risk process facilities globally. The initial focus was towards individual risk contours as these were easier to apply and communicate, but a number of regulators and companies also wish to see societal risk results. This is particularly true for offsite risk predictions. Also some transportation risks only make sense for assessment by societal risk methods as the individual risk can be too low for standard criteria as the total risk is distributed over a long distance over many populations. There are quite significant differences in the global application and this paper will review experiences the authors have found in application examples in Europe, North and South America, the Middle east, and the Far East. The differences are not just to criteria lines on F-N graphs, but also the definition of what populations are included and excluded and this can have significant impact on societal risk results. Finally, offshore oil and gas facilities use a variant of the societal risk concept, the Potential Loss of Life (PLL) statistic, which is the integrated form of the FN curve. This is mainly used for comparative purposes rather than for absolute assessments.